My take on Arlo is that it's a bit quirky, a bit cheeky, cool. Not a classic, mainstream name, something a bit suprising, but not something new, made up, or trendy. It's intelligent, but walks to its own drummer.

Roxanne, in my opinion, fits the bill perfectly. Roxy, on the other hand, take it down a notch. Sassy, yes, but the -y ending robs it of the distinction Arlo owns. But since you don't like the full version, how about.....